Question

2. Empirically determine the value of the resistor that, when
placed across the cell, makes a measurable change in the measured
cell voltage. Calculate the internal resistance of the cell.
With the 120ohms resistor placed across the battery or cell
v=1.471v.
I don't how to measure internal resistance of the cell. please
help?

3. Obtain a DC power supply from the supply cabinet. Measure the
voltage range of each of the power supply outputs.
v=1.612v

4. Set a power supply output to the value of the cell voltage
measured in item 1. Determine the change in this voltage when the
supply is loaded with the resistor used in item 2.
With the 120ohms resistor loaded, Vs=1.582v

5. Design a circuit to light a red light-emitting diode (LED). The
LED current must be about 10{15 mA and no more! The voltage drop
across the diode will be about 1 V, but do not connect a voltage
source directly to the diode; the current in the diode is a very
strong function of the voltage applied across it, and chances
are
that the diode current would exceed the maximum allowed if directly
connected to a supply voltage.
Don't know how to design?help?

NOTE:Nominally, the short lead of the diode is the cathode, i.e.,
the negative lead. However, you can identify the cathode more
reliably by noting that one side of the LED's housing has a at spot
at the base; the terminal closest to this at spot is the
cathode.
This word is important! To an engineer, about means within an order
of magnitude. So, \about 1 V" means somewhere in the range 0.1{10
V. When you turn on the power supply in your circuit, start it at
the low end of that range and slowly increase the voltage until the
LED begins emitting light. Of course, make sure you are monitoring
the current through the LED as you do this so that you do not
exceed the maximum allowable current.

6. Connect a voltage divider to an output of a DC power supply.
Design it to give an output that is 1/3 of the supply voltage.
Furthermore, neither the power ratings of the resistors nor the
current rating of the supply are to be exceeded. The voltage output
of the divider must not change by more than 1% when loaded with 10
k.

7. Design a current divider that provides a 1:2 current split.
Observe the current and power limitations as in the previous item.
Another design constraint is that inserting current meters to
measure the current division ratio must not upset this ratio.

8. Construct a nontrivial resistive circuit with at least two loops
and at least three resistors in each loop. Verify Kirchho's laws
for this circuit both theoretically and empirically. Notice that
this item is more open-ended;
i.e., there is more room for individual initiative. These lab
instructions will be increasingly given in this manner.